Name
Parse::Syntax - Perl extension for Syntax-highlighting progamming languages
Synopsis
use Parse::Syntax;
my $stx = new Parse::Syntax(stx_folder=>'/path/to/stx_folder', lang=>'Perl');
print $stx->parse(<<'END_OF_TEXT'
#!/usr/bin/perl -w
use strict;
if (foo eq bar) {
print "You're screwed\n";
} else {
print "That's the way it is\n";
}
exit 0;END_OF_TEXT
);Description
THIS IS AN ALPHA RELEASE. Anything is subject to change and no backward compatibility is guranteed (yet)
This documentation refers to version 0.01 of Parse::Syntax. Parse::Syntax class is intended to be used in on-line forums and discussion boards (such as perlguru.com?). It highlights the syntax of any programming lanuage provided that it has *.stx file for a spesific language it's expected to parse. Parse::Syntax does not base on any other modules, and rely mainly on Perl's powerfull regex engine.
Main method you need to be aware of is parse() method, which receives one argument, which should be either an expression or a variable which holds the expression to be parsed/highlighted. As of version 0.01, the argument should be only a scalar value. I relise that it whould be nice if we could pass a reference to filehandle and get the method to work on the contents of the file. Well, this feature is comming in the next version. For more detailed list of future features refer to "Todo" section
How it works
For the class to perform as expected, you need to provide it with a *.stx file, which I will refer to as grammar throughout the documentation. When you create the object with new() method, Parse::Syntax scans through the grammar file, and constructs an annonymous hash with all the available key/value pairs. Once you pass the expression to parse(), it calls regexCompiler method internally which in turn compiles and returns a precompiles pattern (using qr// operator). The rest is nothing but matching and substitution. As to their color representation I have a bad news (well, I am not sure how bad it is tho). It relies on CSS (Style Sheet) classes
To understand which classes the parser expects, keep reading. Hopefully, I'm not going to keep it as a secret
Format of the Grammar file
For the grammar file I used *.stx files from my favourite EditPlus 2.10c by ES-Computing. So you can grab one of the *.stx files from your copy of EditPlus and get it to work with *some* minor changes. A standard grammar file that Parse::Syntax expects to deal with looks something like this:
#DELIMITER=,(){}[]-+*/=~!&|<>?:;.
#QUOTATION='
#QUOTATION="
#CONTINUE_QUOTE=n
#LINECOMMENT=#
#LINECOMMENT=
#COMMENTON=
#COMMENTOFF=
#COMMENTON=
#COMMENTOFF=
#ESCAPE=\
#CASE=y
#PREFIX=$
#PREFIX=@
#PREFIX=%
#SUFFIX=
#KEYWORD=Reserved words
continue
do
else
elsif
for
foreach
.......
#KEYWORD=Built-in functions
abs
accept
alarm
atan2
bind
binmode
bless
.....You can add more and more #KEYWORD fields to the above grammar file if you wish so. Forexample, suppose I want standard Perl pragmas and Standard Classes to be highlighted as well. In my text editor, I would add the following lines to the in addition to the above:
#KEYWORD=Pragmas
strict
warnings
...
#KEYWORD=Standard Classes
Autoloader
Autosplit
CGI
AnyDBM_File
......Above I chose Pragmas and Standard Classes as the name to the KEYWORD section. If I was in a bad mood I could name those Compiler Directives and Predefined Modules instead. For Parse::Syntax it doesn't make any difference. But, there is a small "but". Those keywords are used as Style Sheet classes. Forexample, following expression:
use AnyDBM_File;would be parsed as following:
<span class="RESERVED_WORDS">use</span> <span class="STANDARD_CLASSES">AnyDBM_File</span>Of course, you cannot see this unless you view the source of the page in your browser. As you see, it converts the keyword names to uppercase and replaces spaces with underscore. It also implies that you need to provide that page with corresponding Style Sheet classes:
.RESERVED_WORDS {
color: Blue;
}
.STANDARD_CLASSES {
color: #990000;
}At this point I realise that Notion of CSS (Cascading Style Sheets) might sound pretty fearsome for an average Perl programmer. I will try to take this wight off your shoulders hopefully in the next release. Please refer to "Todo" section for more upcomming features. Remember though, NO HTML 4.0 WITHOUT CSS!!!
Methods
new()-
new() method return creates and returns instance of the Parse::Syntax class. It take following arguments:
parse()-
Main method which parses the expression.
set_level()not implemented as of version 0.01-
set_level() method enables you to set the level of hightlighting and goes from 0 for none, up to 3 for maximum
Todo
Listing of the features I am planning to add in the next release
Indentation
More flexibility in setting highlighting level
Ability to choose between CSS and and setting the colors right in the grammar file.
I think this would be nice; seperate highlighting for each grammar file!!! Plus, no CSS hustle for those who cannot get along well with them yet
More polimorphic "parse()" method
Wouldn't it be great if we could pass filehandle to "parse()" and get it to operate on the contents of the file? How about redirecting standard output to a file?
Is there such extension for Perl/Tk?
I am woundering how much effort it would require to make it compatible with Tk.
If you have any other suggestions and/or want to contribute some code to Parse::Syntax, you are more than wellcome. Send me an email to sherzodr@ultracgis.com and we can talk about it
Bugs
Do you think I could fill this section in the next realease and keep this one clean? Cool. I knew you'd let me do that :-)
Author
Sherzod Ruzmetov a.k.a sherzodR, sherzodr@ultracgis.com
Copyright
Copyright 2001, Sherzod Ruzmeto. All rights reserved. This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. Bug reports and comments to sherzodr@ultracgis.com
See Also
Parse::RecDescent, Parse::Token, Parse::yapp, CGI